1. Field of the Invention
The invention disclosed herein relates to apparatus for sorting articles presented in a serial array in accordance with a predetermined physical characteristic of the articles, and more particularly, it relates to such apparatus for performing sorting in an accurate and rapid manner on a large number of such articles while retaining the physical characteristic data in predetermined storage locations and thereafter retrieving such data to perform the sorting for each individual article.
2. Description of the Prior Art
The limitations on a system for sorting articles from a serial array of such articles presented to the system is generally dictated by the size of the memory associated with the system. Data relating to the sorting operation must be stored and retrieved before it is ultimately utilized in discharging the articles from a transporting or conveying portion of the system. Thus, the number of articles which may be handled in a given period of time and the number of sorting ranges is dictated by the size of the memory in the system.
There are many things to remember in a more complex sorting system and very little time to put the representative data into the system memory. For a particular sorting task when a central processing unit is used to do all parts of the job, the job takes a specific amount of processing time. One of the major design questions is whether the central processing unit can accomplish all of the parts of the job in the time allotted. When the speed requirement for sorting approaches the capability limit of the sorting system, the alternatives are presented of either obtaining a higher speed central processing unit and associated circuit components or running the machine slower. The former approach provides a higher level of system expense together with a higher probability of computing errors due to the greater complexity of the circuitry while the latter alternative clearly limits the system's throughput, which is often unacceptable.
A number of systems are currently known which measure certain characteristics of articles presented in a serial array and which store the measurement data so that an operation may be performed by the system at a later point in time when the article has been transported to a predetermined location. One such system is disclosed in French Pat. No. 2,157,137 issued to Tissmetal which describes a system for automatic loading and unloading of a continuous transporter. A transporter or conveyor is divided into a number of adjacent object sites, each of which are subdivided into a specific number of bands. A number of loading stations are positioned at the upstream end of the conveyor and a number of unloading stations are positioned toward the downstream portion of the conveyor. A sensor is provided which detects the passage of each band in each object site as the conveyor moves thereby and which generates pulses connected to a counter. The counter continuously counts up to a number corresponding to the number of bands in each of the object sites and returns to repeat the count from the first band of the ensuing object site. A central memory has as many memory cases as there are object sites. Each memory case is capable of holding the address of an object. When an object is awaiting loading onto the conveyor at a loading station, the object's destination is written into a memory at the loading station. When a loading site which is free of other objects presents itself in front of the loading station, the object is loaded onto the conveyor and the unloading address is written from the loading station memory into the central memory. The unloading address is displaced by one memory case in the central memory each time the conveyor position sensor detects that another entire object site has passed by the sensor. In this fashion, the central memory becomes an image of the conveyor. A code number is associated with each of the unloading stations and a logic device continually compares the code number with the address of the object site which currently presents itself in front of that unloading station. When the object reaches the designated unloading station, the code number and the address of the object will be in agreement and the object will be transferred off of the conveyor at that station. The number of bands into which each object site is divided will dictate the control precision for both conveyor loading and unloading.
U.S. Pat. No. 2,601,915 issued to Eggleston et al discloses an endless belt conveyor for transporting boxes from any one of the number of vertically displaced floors to others of the floors as selected by switches at the floors where the boxes are loaded onto the conveyor. When a box is to be loaded on the conveyor at one of the floor levels, the box is deposited in a loading position and an operator manually actuates a switch which designates the unloading floor. A series of switches including a switch actuated by the weight of the box at the loading station causes loading arms to position the box onto an empty carriage on the conveyor and at the same time a switch actuating pin is set on a timing wheel which rotates in synchronism with the conveyor. When the conveyor reaches the designated unloading station, the pin on the timing wheel actuates another switch which in series with an unloading switch actuated by the arriving carriage completes a circuit for energizing a mechanism which unloads the box at the unloading station. Cams are provided for resetting the switch actuating pins on the timing wheels to their non-actuating positions at the end of each cycle of operation of the timing wheel.
In U.S. Pat. No. 2,666,536 issued to R. L. Smith a sorting control for wood veneer cut to different widths is disclosed. The Smith sorter includes a number of manually set index fingers attached to the conveyor carrying the veneer which are operated by a skilled observer of the passing sheet of veneer to indicate certain positions on the sheet at which transverse cuts need to be made for the purpose of removing flaws in the veneer sheet. A stepper switch is energized and advanced by each of the index pins when they are in the unset position. Thus, the stepper switch is advanced synchronously with the passage of the conveyor. A set index pin not only advances the stepper switch but also closes another switch in series with the stepper switch so that a veneer width sorting circuit is completed and an appropriate mechanism is set into motion which deposits the cut piece of veneer in a bin receiving veneer widths corresponding to the set pin. The stepper switch is also reset by the set index pins. Thus, as long as the index pins are allowed to remain in the inoperative or unset position the stepper switch will be advanced stepwise by the passage of unset index pins. Therefore, the discharge mechanisms for the wider cut veneer widths are associated with the higher stepwise positions of the switch. When a width of veneer is so small as to be unusable, such as when index pins are set which are close together, the cut piece is not engaged by any of the sorting mechanisms but is allowed to tumble off the end of the conveyor into a scrap receiver.
U.S. Pat. No. 3,898,435 issued to Pritchard et al discloses a memory device for use with an egg grading machine wherein a single lane conveyor carries eggs in spaced configuration past a series of packing stations where eggs are to be delivered into pocketed containers in accordance with predetermined weight grades. Signals from weight transducers which indicate the egg weights are transmitted to circuitry wherein they are coded and transferred into a primary electronic memory unit in a predetermined sequence. The eggs are then discharged from the scales into individual egg carriers or buckets on an egg conveyor which transports them toward the series of packing stations. The eggs are discharged at each packing station so that each egg is placed in one of six longitudinally spaced positions in the pocketed containers. The memory device which receives the egg weight data is a serial shift register within which weight data is stored and shifted in response to pulse signals provided by a clock. The shifting of data within the memory unit is independent of the movement of the eggs on the egg conveyor. Data is shifted through the register at a much faster rate than the rate of movement of the eggs along the conveyor path and the two rates are not related. The shifting of the data through the memory register is such that the conveyor in effect stands still during a complete cycle of data through the memory register. A register position counter is operated in conjunction with the memory register. Phase pulses are produced which are in synchronism with the movement of the egg conveyor. One phase pulse is transmitted to the register position counter for each movement of the conveyor which corresponds to the spacing between adjacent egg carrying buckets. Each phase pulse increases the count in the register position counter by one unit and therefore has the effect of shifting all the information in the memory register by one egg bucket length along the conveyor. New weight and grade information is taken into the memory register on the first clock pulse following a phase pulse. At the same time information is read out of the memory register and transmitted to logic circuits at the various packing stations. The logic circuits are configured to recognize data which requires egg dropping at a particular packing station.
In U.S. Pat. No. 2,895,274 issued to Mumma, a machine for grading eggs and delivering the graded eggs to predetermined discharge stations is disclosed. The eggs are initially manually graded for quality by operators who inspect the eggs and place them in predetermined quality racks in accordance with their inspection determinations. The quality inspected eggs are transferred from the quality racks to a conveyor which transports the eggs to a weighing mechanism which makes an egg weight determination. From the weighing mechanism, the eggs are transported to another conveyor which delivers them in serial array to predetermined ones of a series of discharge stations. The appropriate discharge station is determined by both the quality and the weight of each egg. The quality determination of the egg is recorded on a rotating belt in accordance with the rack on which it was placed. The belt moves in synchronism with the conveyor which delivers the eggs to the discharge stations. The weight determination for a given egg is recorded in the same sector of the rotating belt as the one in which the quality determination is recorded. The particular sector of the memory belt in which quality and weight information is recorded corresponds to a particular egg carrying bucket on the conveyor delivering the eggs to the discharge stations. The recordation is accomplished through switch actuation which occurs due to the manual placement of the eggs by the inspector and the automatic weighing operation performed by the weighing mechanism in the machine. The actuated switches energize circuitry which sets pins carried in the corresponding segment of the memory belt. The movement of the belt, in synchronism with the egg delivery conveyor, provides a current record of the quality, weight and position of the eggs. Once the quality and weight graded egg reaches its predetermined discharge station control of the egg at that particular discharge station is assumed by a secondary memory which operates to cause the eggs to be released from the distributing conveyor so that they are deposited in a succession of pockets in a grid-like carton beneath the conveyor. Both the primary and the secondary memories for the egg grading machine are dependent upon mechanically actuated switches which function to energize solenoids for setting memory pins in mechanical memory. The memory pins in turn function to actuate switches which energize solenoids providing for appropriate mechanical operations to discharge the eggs from the conveyor.